Pneumatic rpm regulator for fuel injection pumps

ABSTRACT

The fuel rack of a fuel injection pump is controlled by the motion of a diaphragm which separates a vacuum chamber communicating with a venturi in the air intake tube of an internal combustion engine from an additional chamber communicating with the ambient atmosphere through a continuously open throttle bore and an inwardly opening check valve.

[ June 28, 1974 United States Patent 1191 Suda et al.

12/1939 Weber et al.

[ PNEUMATIC RPM REGULATOR FOR FUEL 2,183,035 I M 140 MP 2,817,325 12 1957 eissner...................... 1 140 MP INJECTION PUMPS 3,736,912 6/1973 Okura et 123/140 MP [75] Inventors: Toshi Suda, Nagoya; Takuji Isomura, Toyota, both of Japan [73] Assignee: Nippondenso Co. Ltd., Kariya Shi,

Primary ExaminerLaurence M. Goodridge Assistant ExaminerCort Flint Alchl Japan Attorney, Agent, or FirmEdwin E. Greigg [22] Filed: Oct. 2, 1972 Appl. N0.: 293,831

ABSTRACT [30] Foreign Application Priority Data 46-90692 The fuel rack of a fuel injection pump is controlled by Oct. 2, l97l the motion of a diaphragm which separates a vacuum :[52] US. 123/140 MP, 123/140 MC chamber communicating with a venturi in the air in- [51] Int.

F02d 1/04 take tube of an internal combustion engine from an Field of searc 123/140 140 MP additional chamber communicating with the ambient atmosphere through a continuously open throttle bore and an inwardly opening check valve.

' References Cited UNITED STATES PATENTS 2,132,446 Schweizer.................... 123/140 MP 1 Claim, 2 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to a pneumaticrpm regulator for a fuel injection pump and is of the type that has a vacuum chamber and an adjoining additional chamber which is separated from the vacuum chamber by means of a diaphragm and whichis in communication with the ambient atmosphere.

In case a conventional diesel engine is suddenly accelerated, the injected fuel quantities will abruptly become larger than the fuel quantities required by the engine and, as a result, the known black exhaust smoke is generated.

I OBJECT AND SUMMARY OF THE INVENTION It' is an object of the invention to provide an improved pneumatic rpm regulator of the afore-outlined type in which, exclusively in case of a sudden acceleration of the engine, the fuel rack responds with a delay to the rpm regulator for preventing a sudden increase in the injected fuel quantities, while the injected fuel quantities required by the engine are thereafter gradually increased.

Briefly stated, according to the invention, the'additional chamber communicates with the ambient atmosphere by means of a small throttle bore and has a check valve that opens inwardly. The throttle bore ensures that the diaphragm separating the vacuum chamber from the additional chamber and connected to the fuel rack causes the fuelrack to respond with a delay during sudden acceleration of the engine, while the check valve ensures that the fuel rack response is not delayed during acceleration of the engine.

BRIEF DESCRIPTION or THE DRAWING The invention will be better understood'as well as further objects and advantages become more apparent from theensuing detailed specification of a preferred, although exemplary embodiment taken in conjunction with the drawing, wherein:

FIG. 1- is a sectional view of the preferred embodiment and FIG. I 2 is a diagram illustrating the characteristic curves of the regulator.

Turning now to FIG. 1, there is illustrated a pump housing 1 and a regulator housing 2. Within the housing 2 there is transversally disposed a diaphragm 4 which is connected with a fuel rack 3 by means of a rod 6. When the fuel rack 3 is moved towards the left (as viewed in FIG. 1 the fuel quantities increase. The diaphragm 4 and the regulator housing 2 define a vacuum chamber 2 which, by means of a conduit 10, is in communication with a venturi (not shown) disposed in the air intake tube of the internal combustion engine. The venturi generates in. the vacuum chamber 2 a vacuum which is in equilibrium with a regulator spring 5. The diaphragm 4 separates the vacuum chamber 2 from an adjoining additional chamber 12. The wall of the latter is provided with a small throttle bore 7 having a diameter d (1: and an adjacent check valve 8 which is formed of a movable valve head 11 and a valve spring 9 urging the valve head 11 into a closed position. The check valve 8 opens inwardly.

In the description that follows there will be explained in detail the mode of operation of the afore-described preferred embodiment.

. Turning now to FIG. 2, along the ordinate there is measured the vacuum A P generated by the venturi.

Along the right-hand portion of the abscissa there is measured the position RW of the fuel rack 3, while along the left-hand side of the abscissa there is shown the pump rpm N. On the right hand side of the abscissa the arrow indicates the direction of increasing fuel delivery. 0 and 0 indicate the opening angle of a butterfly valve installed in the venturi. It is noted that 0 0,. In case of slow idling, first the vacuum A P and the spring 5 are in equilibrium in the position b of the fuel rack 3 and in the position b of the butterfly valve. If now there is a sudden acceleration'of the engine, the vacuum A P drops until the fuel rack and the butterfly valve reach a position a, a, respectively. If it is assumed that as a result of this occurance the diaphragm 4 is deflected towards the left as viewed in FIG. 1, then, by virtue of the small bore 7 provided in the wall of the chamber 7 the air forced out of the chamber 12 is throttled and thus the diaphragm 4 is braked in its normally sudden leftward movement. Stated differently, for the leftward displacement of the fuel rack 3 a certain period of time (delay) is needed. Thus, since the injected fuel quantities increase only very slowly (that is, in a progressive manner), no excess fuel is obtained and, as a result, no black smoke is generated. In normal operation the change of the vacuum A P occurs only very slowly and thus the diaphragm 4 follows accordingly and responds to the usual rpm changes. When the diaphragm 4 moves towards the right for a downward rpm regulation (rpm reduction) during the high rpm operation, then no braking effect will be present, since the greater ambient pressure will cause an opening of the check valve 8. The latter thus ensures that during the regulation of high rpms the response of the rpm regulation (rpm reduction) is rapid.

We claim: a

1. In a pneumatic rpm regulator associated with a fuel injection pump of an, internal combustion engine, said pump having a fuel rack, said regulator being of the known type that includes (a) a vacuum chamber, (b) an additional chamber, (c) means effecting communication between said additional chamber and the ambient atmosphere, (d) a diaphragm separating said chambers from one another and (e) means connecting said diaphragm to said fuel rack for causing displacement of the latter upon deflection of said diaphragm, the improvement comprising:

A. means defining a throttle bore in said additional chamber, said throttle bore maintaining a continuous communication between said additional chamber and the ambient atmosphere and B. a check valve provided for in said additional chamber and designed to open inwardly, said check valve, when open, maintaining communication between said additional chamber and the ambient atmosphere; said throttle bore and said check valve constituting said means effecting communication between said additional chamber and the ambient atmosphere, such that during sudden engine acceleration said throttle bore causes a delay in the response of said fuel rack due to the throttling effect of the air from said additional chamber through said throttle bore to the ambient atmosphere, while during engine deceleration said check valve ensures nondelayed response of said fuel rack due to the passage of ambient air through said check valve and into said additional chamber. 

1. In a pneumatic rpm regulator associated with a fuel injection pump of an internal combustion engine, said pump having a fuel rack, said regulator being of the known type that includes (a) a vacuum chamber, (b) an additional chamber, (c) means effecting communication between said additional chamber and the ambient atmosphere, (d) a diaphragm separating said chambers from one another and (e) means connecting said diaphragm to said fuel rack for causing displacement of the latter upon deflection of said diaphragm, the improvement comprising: A. means defining a throttle bore in said additional chamber, said throttle bore maintaining a continuous communication between said additional chamber and the ambient atmosphere and B. a check valve provided for in said additional chamber and designed to open inwardly, said check valve, when open, maintaining communication between said additional chamber and the ambient atmosphere; said throttle bore and said check valve constituting said means effecting communication between said additional chamber and the ambient atmosphere, such that during sudden engine acceleration said throttle bore causes a delay in the response of said fuel rack due to the throttling effect of the air from said additional chamber through said throttle bore to the ambient atmosphere, while during engine deceleration said check valve ensures nondelayed response of said fuel rack due to the passage of ambient air through said check valve and into said additional chamber. 